Prior art devices address particular issues in open-heart surgery such as how to occlude the aorta while on cardiopulmonary bypass (CPB). There are two aspects of such devices that involve the aorta during CPB. One is to occlude the aorta to allow the pump to perfuse the body without entering the left ventricle or ascending aorta. This is usually accomplished with a clamp (called a cross-clamp) placed across the ascending aorta above the coronary ostia. Many of the prior art devices provide alternate ways to accomplish this occlusion from inside the aorta, for example, with a balloon directly inserted or passed intravascularly as a catheter. The second important part of CPB involves administering the cardioplegia in the ascending portion of the aorta below the cross clamp where it is trapped between the cross clamp and the aortic valve forcing it down the coronary arteries to protect the myocardium during heart stoppage. Prior art methods are known for administering the cardioplegia and clamping or occluding the aorta. Examples of such prior art devices are provided in the following patents.
U.S. Pat. No. 6,267,747 (Samson et al.) discloses an aortic catheter system having an aortic root balloon that occludes the aorta for the delivery of cardioplegia during cardiopulmonary bypass and may be used to help maintain the competency of regurgitant aortic valves. The balloon occluder described by Samson et al. is inserted from the groin to allow occlusion of the ascending aorta and to block the aortic valve. Samson et al. disclose the use of a porous aortic root balloon that is capable of occluding the aorta, delivering cardioplegia, providing tactile feedback, and helping to maintain the competency of regurgitant aortic valves. With respect to FIG. 12, Samson et al. describe that the most distal balloon may conform to the cusps of the aortic valve to prevent cardioplegia from entering the ventricle through the aortic valve. Samson et al. also disclose that any desirable or practical collapsible valve may be used; however, Samson et al. do not describe the use of a foldable umbrella type device that may be delivered through the aortic root via a standard cardioplegia cannula for deployment at the aortic valve.
U.S. Pat. No. 6,673,040 (Samson et al.) discloses the placement of umbrella type flow control valves in the aorta for arterial perfusion during non-surgical procedures. Generally, Samson et al. teach placing inflatable occlusion balloons in the patient's ascending aorta between the coronary arteries and the brachiocephalic artery. Again, no umbrella type device inserted through the aortic root via a standard cardioplegia cannula is taught.
U.S. Pat. No. 6,090,096 (St. Goar et al.) also disclose a catheter balloon occlusion system, in this case inserted from the left atrium to the ascending aorta to occlude the aorta as a cross clamp would above the coronary ostia. The occlusion member may alternatively be a collapsible one-way valve with one or more movable leaflets, an umbrella-like expanding membrane, or other mechanical occlusion device. However, the device disclosed by St. Goar is not used for valve blockage but, instead, the balloon is used to occlude the ascending aorta between the brachiocephalic artery and the coronary ostia. The catheter itself is introduced through the wall of the heart into the left atrium, advanced through the mitral valve, and into the ascending aorta.
U.S. Pat. No. 5,458,574 (Machold et al.) discloses a similar system to the St. Goar et al. occlusion system for isolating the coronary arteries using a catheter with two expandable occlusion devices during cardiopulmonary bypass.
U.S. Pat. No. 6,638,293 (Makower et al.) discloses an umbrella-type embolic device for occluding the ascending aorta. Makower et al. do not teach blocking flow in the aorta across the aortic valve.
Other techniques are known in the art for aortic occlusion above the aortic valve (cross clamp equivalents). For example, U.S. Pat. No. 6,231,544 (Tsugita et al.) discloses a cardioplegia balloon cannula for aortic occlusion and filtering with a “cape” cannula, while U.S. Pat. No. 6,176,851 (Tsugita et al.) discloses a cardioplegia occluder which opens downstream from a solution introducing port to isolate the aorta from other vasculature. U.S. Pat. No. 6,159,178 (Sharkawy et al.) further discloses methods and devices for occluding the ascending aorta and delivering cardioplegic fluid to arrest the heart, while U.S. Pat. No. 6,149,578 (Downey et al.) discloses an expandable device for occluding the ascending aorta. U.S. Pat. No. 6,117,105 (Bresnaham et al.) discloses an aortic catheter including valve occlusion members deployed adjacent the aortic valve.
However, the devices of these prior art patents address a separate problem to that addressed by the device described herein. As will be explained below, the present invention addresses the situation where the aortic valve is not fully competent. In this setting, administration of the cardioplegia to the ascending aorta can enter the left ventricle below the coronary arteries where it causes two problems: (1) expansion of the left ventricular size which increases oxygen demand and (2) less cardioplegia goes into the coronary arteries. The net effect is inadequate myocardial protection during the operation. The present invention addresses this separate problem in the art.